From 68f063bf3fb9ca7dc585e18250ba7a75f40a245f Mon Sep 17 00:00:00 2001
From: Gary Guo <gary@garyguo.net>
Date: Sat, 14 May 2022 02:46:46 +0100
Subject: [PATCH 1/2] Use Rust ABI for `__rust_start_panic` and `_{rdl,rg}_oom`

---
 library/alloc/src/alloc.rs      | 4 ++--
 library/panic_abort/src/lib.rs  | 2 +-
 library/panic_unwind/src/lib.rs | 2 +-
 library/std/src/panicking.rs    | 2 +-
 4 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/library/alloc/src/alloc.rs b/library/alloc/src/alloc.rs
index 39f8f1d5a0ec7..da61ff1e7512a 100644
--- a/library/alloc/src/alloc.rs
+++ b/library/alloc/src/alloc.rs
@@ -398,13 +398,13 @@ pub mod __alloc_error_handler {
 
     // if there is no `#[alloc_error_handler]`
     #[rustc_std_internal_symbol]
-    pub unsafe extern "C-unwind" fn __rdl_oom(size: usize, _align: usize) -> ! {
+    pub unsafe fn __rdl_oom(size: usize, _align: usize) -> ! {
         panic!("memory allocation of {size} bytes failed")
     }
 
     // if there is an `#[alloc_error_handler]`
     #[rustc_std_internal_symbol]
-    pub unsafe extern "C-unwind" fn __rg_oom(size: usize, align: usize) -> ! {
+    pub unsafe fn __rg_oom(size: usize, align: usize) -> ! {
         let layout = unsafe { Layout::from_size_align_unchecked(size, align) };
         extern "Rust" {
             #[lang = "oom"]
diff --git a/library/panic_abort/src/lib.rs b/library/panic_abort/src/lib.rs
index 2bcb3182a7bf2..0a1aa7bb3c833 100644
--- a/library/panic_abort/src/lib.rs
+++ b/library/panic_abort/src/lib.rs
@@ -30,7 +30,7 @@ pub unsafe extern "C" fn __rust_panic_cleanup(_: *mut u8) -> *mut (dyn Any + Sen
 
 // "Leak" the payload and shim to the relevant abort on the platform in question.
 #[rustc_std_internal_symbol]
-pub unsafe extern "C-unwind" fn __rust_start_panic(_payload: *mut &mut dyn BoxMeUp) -> u32 {
+pub unsafe fn __rust_start_panic(_payload: *mut &mut dyn BoxMeUp) -> u32 {
     // Android has the ability to attach a message as part of the abort.
     #[cfg(target_os = "android")]
     android::android_set_abort_message(_payload);
diff --git a/library/panic_unwind/src/lib.rs b/library/panic_unwind/src/lib.rs
index 7f05c82ac284b..4ae5f8ae4468d 100644
--- a/library/panic_unwind/src/lib.rs
+++ b/library/panic_unwind/src/lib.rs
@@ -104,7 +104,7 @@ pub unsafe extern "C" fn __rust_panic_cleanup(payload: *mut u8) -> *mut (dyn Any
 // Entry point for raising an exception, just delegates to the platform-specific
 // implementation.
 #[rustc_std_internal_symbol]
-pub unsafe extern "C-unwind" fn __rust_start_panic(payload: *mut &mut dyn BoxMeUp) -> u32 {
+pub unsafe fn __rust_start_panic(payload: *mut &mut dyn BoxMeUp) -> u32 {
     let payload = Box::from_raw((*payload).take_box());
 
     imp::panic(payload)
diff --git a/library/std/src/panicking.rs b/library/std/src/panicking.rs
index f1baf077580e6..9b045980d4543 100644
--- a/library/std/src/panicking.rs
+++ b/library/std/src/panicking.rs
@@ -47,7 +47,7 @@ extern "C" {
 }
 
 #[allow(improper_ctypes)]
-extern "C-unwind" {
+extern "Rust" {
     /// `payload` is passed through another layer of raw pointers as `&mut dyn Trait` is not
     /// FFI-safe. `BoxMeUp` lazily performs allocation only when needed (this avoids allocations
     /// when using the "abort" panic runtime).

From fbb3c19e0347b21d84b428981e930401b7f81b76 Mon Sep 17 00:00:00 2001
From: Gary Guo <gary@garyguo.net>
Date: Sat, 14 May 2022 02:49:12 +0100
Subject: [PATCH 2/2] Use re-export instead of inline wrapper in libunwind

This ensures that there are no calls to `C-unwind` function in libunwind.
---
 library/unwind/src/libunwind.rs | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/library/unwind/src/libunwind.rs b/library/unwind/src/libunwind.rs
index 432628613f586..7b78bda424bb0 100644
--- a/library/unwind/src/libunwind.rs
+++ b/library/unwind/src/libunwind.rs
@@ -264,10 +264,7 @@ if #[cfg(not(all(target_os = "ios", target_arch = "arm")))] {
         pub fn _Unwind_SjLj_RaiseException(e: *mut _Unwind_Exception) -> _Unwind_Reason_Code;
     }
 
-    #[inline]
-    pub unsafe fn _Unwind_RaiseException(exc: *mut _Unwind_Exception) -> _Unwind_Reason_Code {
-        _Unwind_SjLj_RaiseException(exc)
-    }
+    pub use _Unwind_SjLj_RaiseException as _Unwind_RaiseException;
 }
 } // cfg_if!